1. Technical Field
The present disclosure relates to a vehicle control device and a vehicle control method.
2. Related Art
As related art, for example, Japanese Unexamined Patent Application Publication (JP-A) No. H10-295004 discloses the following technique. When only one of four driving wheels is slipping, an output torque that is to be distributed to the slipping wheel if the slip is not generated is distributed to a non-slip wheel located on the same side, left side or right side, of the slipping wheel.
In addition, for example, Japanese Unexamined Patent Application Publication (JP-A) No. 2011-130629 discloses the following technique. In executing differential limiting between the respective wheels (axles) in order to improve the running through performance and stability of an electric vehicle whose front and rear, left and right wheels can be driven independently, a correction torque is computed with a high gain with respect to a rotation difference of the wheels on which differential limiting is executed. The thus obtained value is limited by an upper limit that is computed separately to set the resulting value as a final output value.
However, with the technique disclosed in the above JP-A No. H10-295004, it is determined whether or not each wheel is slipping on the basis of the absolute value of angular acceleration, and when a slip is generated, the torque is distributed by controlling the output torque. Consequently, the distributed motor torque vibrates, resulting in degradation in drivability.
In addition, with the technique disclosed in the above JP-A No. 2011-130629, when the front wheel slips and the rotation speed thereof is increased, feedback control is performed with a high gain so that the response of transferring the torque to the rear wheel can be increased. In this case, because the motors and tires vibrate significantly, it is necessary to limit the torque transfer amount by providing an upper limit. Consequently, it becomes difficult to transfer a sufficient torque at the time of slip generation, and it is difficult to suppress a slip surely.